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The most difficult types of measurements are those that exercise the
full dynamic range of the 37xxxE, such as filters (Figure 8-11. Filter
measurements are examples of where one must observe both low-in
-
sertion loss (in the passband) and high attenuation (in the stop band).
There are two techniques that you can use to optimize the sig-
nal-to-noise ratio. They are (1) maximizing the RF signal level and (2)
using signal enhancement.
To maximize the RF signal level, use the default settings of the
37xxxE.
The 37xxxE provides two enhancements for improving the sig-
nal-to-noise ratio: IF bandwidth reduction and averaging.
Reducing the IF bandwidth is a primary method for enhancing accu
-
racy. The 37xxxE has a choice of four bandwidths available from the
front panel: Maximum (10 kHz), Normal (1 kHz), Reduced (100 Hz),
and Minimum (10 Hz). The noise level should decrease by a factor
equal to the square root of the IF bandwidth. Using IF Bandwidth re
-
duction makes for faster measurements than with the use of an equiv
-
alent amount of averaging.
37xxxE OM 8-15
MEASUREMENTS LOW LEVEL AND GAIN
P A S S B A N D
< 1 d B
F R E Q U E N C Y
d B
B A N D P A S S F I L T E R
0 d B
S T O P B A N D
> 5 0 d B
S
2 1
Figure 8-11. Filter Measurements